Quartz crystal, quartz device using the same, intermediate wafer for quartz device, and method for manufacturing quartz crystal.

Abstract

The present invention provides a quartz crystal, a quartz device, and an intermediate wafer having a novel shape suitable for use in the manufacture of quartz devices. [Solution] The quartz piece 10 has the XZ' plane defined by the X-axis and Z'-axis of the quartz as its main surfaces 10ca and 10cb, and the Y'-axis of the quartz as the thickness direction, and is an AT-cut quartz piece with a square shape in plan view. When one of the sides along the X-axis is defined as the first side surface 10aa of the X-axis and the other as the second side surface 10ab of the X-axis, and when one of the sides along the Z'-axis is defined as the first side surface 10ba of the second axis and the other as the second side surface 10bb of the second axis, each of these sides is composed of a crystal plane 10e derived from the quartz and a plane having a contour 10fa parallel to the normal 10cc of the main surface of the quartz piece 10 (a plane perpendicular to the main surface).

Description

Technical Field

[0001] The present invention relates to a crystal piece suitable for use in the manufacture of crystal devices such as crystal oscillators, crystal oscillators with temperature sensors, and crystal oscillators (including crystal oscillators with temperature compensation functions), the crystal device, an intermediate wafer suitable for use in the manufacture of the crystal device, and a method for manufacturing the crystal piece.

Background Art

[0002] With the miniaturization and high-frequencyization of communication devices, the miniaturization and high-frequencyization of crystal devices, which are the frequency reference sources of communication devices, have become increasingly necessary. Therefore, a small and thin crystal piece constituting the crystal device is desired. For this reason, it is widely practiced to manufacture an AT-cut crystal piece using photolithography technology and wet etching technology. An example thereof is described, for example, in paragraphs 42 to 48 and FIG. 3 of Patent Document 1.

[0003] In the crystal piece disclosed in Patent Document 1, at least one of the side surfaces at both ends along the X axis of the crystal includes at least four surfaces, and the angle formed by the two surfaces constituting the end portion on the side surface is an obtuse angle (claims 6, 7, etc. of Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Photolithography and wet etching are indeed useful technologies for miniaturizing and increasing the frequency of quartz crystals. However, with these technologies, the external shape of the quartz crystal may impair the properties of the quartz device due to the anisotropy of the crystal axis with respect to wet etching. Specifically, the sides of quartz crystals formed by photolithography and wet etching technologies, as described in Patent Document 1, have inclined surfaces that are tilted relative to the main surface of the quartz crystal and have a convex shape toward the outside of the crystal crystal, due to the crystallinity of the quartz. On the other hand, the region used as the vibration region of the quartz crystal is the part where the main surfaces are parallel to each other, so the part of the quartz crystal with inclined surfaces does not function as a vibration region. Therefore, the longer the dimension parallel to the main surface of the quartz crystal in the part of the side that contains many inclined surfaces, the narrower the vibration region becomes, which is undesirable in terms of the design freedom of the quartz crystal and the improvement of the properties of the quartz device. As quartz devices become smaller, the quartz crystal itself becomes smaller and the proportion of the inclined surface in the quartz crystal increases, so the above problem becomes more serious. This application has been made in view of the above points, and therefore the object of this application is to provide a quartz crystal having a novel shape suitable for use in the manufacture of a quartz device, a quartz device using the same, an intermediate wafer for a quartz device, and a method for manufacturing a quartz crystal. [Means for solving the problem]

[0006] To achieve this objective, according to the first invention of this application, a quartz piece has a first axis-second axis plane defined by a first axis originating from the X axis of the quartz and a second axis originating from the Z axis of the quartz as its main plane, and a third axis originating from the Y axis of the quartz as the thickness direction, and in a quartz piece that is rectangular in shape when viewed from above, When one of the surfaces of the quartz crystal that intersects the first axis is defined as the first surface of the first axis and the other as the second surface of the first axis, and when one of the surfaces of the quartz crystal that intersects the second axis is defined as the first surface of the second axis and the other as the second surface of the second axis, The first side surface of the first axis and the second side surface of the first axis are each composed of a crystal plane derived from quartz and a plane having a contour parallel to the normal of the main plane. The first side surface of the second axis and the second side surface of the second axis are characterized in that they are composed of a crystal plane derived from quartz and a plane having a contour parallel to the normal of the main surface, or are composed of a crystal plane derived from quartz that is not parallel to the normal of the main surface.

[0007] In this invention, a surface having a contour parallel to the normal of the main surface refers to a surface having a contour that is exactly parallel to the normal when viewed along the normal of the surface. In other words, a surface having a contour parallel to the normal of the main surface refers to a surface that is exactly perpendicular to the main surface or approximately perpendicular to it (hereinafter, these may also be referred to as perpendicular surfaces). Furthermore, in this invention, a perpendicular surface may be an amorphous surface, a crystalline surface, or a surface in which amorphous and crystalline surfaces are mixed. Furthermore, the crystalline and amorphous surfaces referred to in this invention may include minute irregularities on their surfaces, for example, irregularities with height differences of several nanometers to about 1 μm, preferably several tens of nanometers to about 1 μm. This is because it is expected that unwanted vibrations relative to the principal vibration of the quartz crystal can be reduced.

[0008] Furthermore, in carrying out this first invention, the quartz piece of the first invention is typically a quartz piece that vibrates in thickness-slip mode, and is a so-called double-rotation quartz piece, such as an AT-cut quartz piece or an SC-cut vibrating piece. When the quartz piece is an AT-cut quartz piece, the first axis is the X-axis of the quartz, the second axis is the Z'-axis of the quartz, and the third axis is the Y'-axis of the quartz. Here, the Z'-axis and Y'-axis are, as is well known, the angles that the AT-cut quartz piece deviates from the Z-axis and Y-axis of the quartz, depending on the cutting angle from the quartz rough. Furthermore, the first invention can also be applied to quartz crystals whose main plane is the first axis-second axis plane, which originates from the X-axis of the quartz crystal and the second axis, which originates from the Y-axis of the quartz crystal, and whose third axis, which originates from the Z-axis of the quartz crystal, is in the thickness direction. For example, the first invention can also be applied to contour-type quartz crystals such as GT cut crystals and bending-type quartz crystals such as tuning fork-type quartz oscillators.

[0009] Furthermore, according to the second invention of this application, the invention of a quartz device, it is characterized by comprising a quartz crystal piece of the first invention, a quartz vibrating piece having excitation electrodes provided on the main surfaces of the front and back of the quartz crystal piece, and a container enclosing the quartz vibrating piece. In this second invention, the crystal device typically refers to a quartz resonator, a quartz resonator with a temperature sensor, or a quartz oscillator (including a quartz oscillator with a temperature compensation function). Furthermore, according to the third invention of this application, an intermediate wafer for a quartz device, the invention is characterized by comprising a quartz wafer having a large number of quartz vibrating pieces arranged in a matrix, each of which is a quartz piece according to the first invention and an excitation electrode provided on both sides of the quartz piece.

[0010] Furthermore, when manufacturing the quartz crystal piece of the first invention described above, it is preferable to manufacture it using the following method, which corresponds to the fourth invention of this application. In other words, it is preferable to carry out the process by including the steps of: preparing a quartz wafer; irradiating the quartz wafer with laser light, preferably ultrashort pulse laser light, along the planned outer edge portion of the quartz piece to form a crystallinity loss region in the thickness direction of the quartz wafer at the planned outer edge portion; and immersing the quartz wafer, in which the crystallinity loss region has been formed, in a wet etching etchant, such as a hydrofluoric acid-based etchant, to remove the region including the outer edge portion of the quartz wafer and to penetrate the quartz wafer to form the outer shape of the quartz piece. Furthermore, when carrying out this manufacturing method, it is preferable to control the dimension in the thickness direction of the quartz wafer on the vertical surface (the dimension shown as t1 in Figure 1, etc.) by adjusting the immersion time of the quartz wafer in the etchant. More specifically, it is preferable to control the ratio between the dimension in the thickness direction of the quartz wafer on the vertical surface (the dimension shown as t1 in Figure 1, etc.) and the crystal planes derived from quartz connected to the vertical surface by adjusting the immersion time of the quartz wafer in the etchant. [Effects of the Invention]

[0011] According to the first invention of this application, the first side surface of the first axis, the second side surface of the first axis, and optionally the first and second side surfaces of the second axis are composed of a crystal plane derived from the quartz and a vertical plane having a contour parallel to the normal to the main surface of the quartz. Therefore, compared to the case where these sides are composed only of inclined planes derived from the crystal plane of the quartz, the proportion of inclined planes on the side surface can be reduced, thus reducing the narrowing of the area where the two main surfaces of the quartz face each other (the area that can be used as a vibration region) compared to the conventional invention. Generally, a wider vibration region in a quartz vibrator makes it easier to improve the electrical characteristics of the quartz vibrator and also increases the design freedom of the quartz vibrator, so the present invention makes it easier to obtain these advantages. Therefore, it is possible to provide a quartz vibrator with a novel shape that is suitable for use in the manufacture of quartz devices. Furthermore, according to the second invention of this application, the invention of a quartz device, it is possible to realize a quartz device with superior characteristics compared to conventional devices. Furthermore, the intermediate wafer for quartz devices, which is the third invention of this application, enables the mass production of quartz devices with superior characteristics compared to conventional devices. Furthermore, according to the fourth invention of this application, which is a method for manufacturing quartz crystals, the quartz crystals of the first invention can be easily manufactured. [Brief explanation of the drawing]

[0012] [Figure 1] (A) to (C) are diagrams illustrating the crystal piece 10 of the embodiment. [Figure 2] Figures (A) to (C) are diagrams that explain the rationale for the angles θa, θb, etc., as defined in this invention. [Figure 3] This figure illustrates a different structural example from the crystal piece 10 in the embodiment of both end faces along the Z' axis. [Figure 4] This is a diagram (SEM image) showing the +X plane, -X plane, and Z' plane of the quartz crystal piece 10 of the embodiment. [Figure 5] This is a diagram illustrating the comparative example quartz crystal 100. [Figure 6] This is a diagram illustrating the crystal device 20 of the embodiment. [Figure 7]It is a diagram for explaining the crystal device 30 of another embodiment. [Figure 8] It is a diagram for explaining examples of the electrical characteristics of each of the crystal device 20 of the embodiment and the crystal device of the comparative example. [Figure 9] It is a diagram for explaining a preferable dimensional example of the crystal piece 10 having an oscillation frequency of 76.8 MHz. [Figure 10] (A) to (D) are diagrams for explaining an embodiment of the manufacturing method which is the fourth invention, and diagrams for explaining the intermediate wafer 50X of the embodiment of the third invention.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of each invention of this application will be described with reference to the drawings. Note that each drawing used in the description only schematically shows the inventions to such an extent that they can be understood. Also, in each drawing used in the description, the same components are denoted by the same reference numerals, and the description thereof may be omitted. Further, the shapes, materials, manufacturing method examples, etc. described in the following embodiments are merely preferred examples within the scope of this invention. Therefore, the present invention is not limited only to the following embodiments.

[0014] 1. Crystal Piece of Embodiment 1-1. Structural Outline The embodiment of the quartz crystal 10 will be described with reference to Figures 1(A) to (C). Here, Figure 1(A) is a top view of the quartz crystal 10, Figure 1(B) is a cross-sectional view of the quartz crystal 10 cut along the PP line in Figure (A), and Figure 1(C) is a cross-sectional view of the quartz crystal 10 cut along the QQ line in Figure (A). However, in the case of Figure 1(A), the quartz crystal 10 is shown in the state of a quartz vibrating crystal with excitation electrodes 11 attached to the main surfaces 10c on both sides. Also, what is shown as 11a in Figure 1(A) is an extraction electrode drawn out from the excitation electrode 11 to one side of the quartz crystal 10. All of Figures 1(A) to (C) are images taken using an electron microscope (SEM) of the embodiment of the quartz crystal 10. Also, the coordinate axes X, Y', and Z' shown in Figure 1(A) represent axes derived from the crystal axes X, Y, and Z of the quartz. The dashes for the Z' and Y' axes are due to the fact that the quartz piece 10 used in this embodiment is an AT-cut quartz piece, and they represent axes that are shifted from the Z and Y axes of the quartz due to the cutting angle of the AT cut.

[0015] The crystal piece 10 of the embodiment has a first axis 10a derived from the X axis of the crystal and a second axis 10b derived from the Z axis of the crystal, with the first axis-second axis plane defined by these two axes as the main surfaces 10ca and 10cb, and a third axis 10d derived from the Y axis of the crystal as the thickness direction, and is a crystal piece with a rectangular shape in plan view. Specifically, in this case, the crystal piece 10 of the embodiment is an AT-cut crystal piece with a rectangular planar shape, where the X axis direction of the crystal is the longer side and the Z' axis direction of the crystal is the shorter side. Therefore, the first axis 10a is the X axis of the crystal, the second axis 10b is the Z' axis of the crystal, and the third axis 10d is the Y' axis of the crystal. Furthermore, in this quartz piece 10, the two main surfaces 10ca and 10cb are parallel to each other and represent the region where the thickness of the quartz piece 10 is t. When the crystal piece 10 is constructed such that one side (in this case, the +X side) intersecting the first axis (in this case, the X-axis of the crystal) is defined as the first side 10aa of the first axis, and the other side (in this case, the -X side) is defined as the second side 10ab of the first axis, and one side (in this case, the Z' axis) intersecting the second axis (in this case, the Z' axis of the crystal) is defined as the first side 10ba of the second axis, and the other side is defined as the second side 10bb of the second axis, each side has the following configuration.

[0016] In other words, as shown in Figure 1(B), the first side surface 10aa and the second side surface 10ab of the first axis are each composed of crystal planes 10e1 and 10e2 derived from quartz, which will be described in detail later, and a plane 10f (also called a vertical plane 10f) that is connected to them and has a contour 10fa parallel to the normal 10cc of the main plane. Furthermore, as shown in Figure 1(C), the first side surface 10ba and the second side surface 10bb of the second axis are, in this embodiment, composed of a crystal plane 10e derived from quartz and a plane 10f (also called a vertical plane 10f) connected thereto, which has a contour 10fa parallel to the normal 10cc of the main plane. The following describes each side surface 10aa, 10ab, 10ba, and 10bb in detail.

[0017] 1-2. The +X side and -X side of the crystal piece First, referring to Figure 1(B), the structure of the first side surface 10aa and the second side surface 10ab of the first axis will be described.

[0018] 1-2-1. First side surface 10aa of the first axis (+ X side surface) In this case, the first side surface 10aa of the first axis is the +X side of the quartz crystal, which is one of two sides that intersect the X-axis of the quartz crystal. As shown on the left side of Figure 1(B), this first side surface 10aa of the first axis is composed of a crystal plane 10e1 (first crystal plane 10e1) that is in contact with one main surface 10ca of the quartz piece 10, a crystal plane 10e2 (second crystal plane 10e2) that is in contact with the other main surface 10cb of the quartz piece 10, and a plane 10f (also called a vertical plane 10f) that lies between these two crystal planes 10e1 and 10es and has a contour 10fa parallel to the normal 10cc of the main surface. And, when a cross-section cut along the X-Y' plane determined by the X-axis and the Y'-axis of the crystal piece 10 defines an angle θa between the vertical plane 10f and the first crystal plane 10e1 connected thereto at the plus-side end of the X-axis, and defines an angle θb between the vertical plane 10f and the second crystal plane 10e2 connected thereto, θa is an angle in the range of 90 < θa ≦ 130°, more specifically 114 ≦ θa ≦ 130°, and θb is an angle in the range of 90 < θb ≦ 130°, more specifically 114 ≦ θb ≦ 130°. Note that either θa = θb or θa ≠ θb may occur.

[0019] The reason why the angles θa and θb should be within the above ranges is as follows. This explanation will be given with reference to FIGS. 2(A) and (B). Here, FIG. 2(A) shows an image of the AT-cut crystal piece 10 with a thickness of ta processed by a manufacturing method using a laser and wet etching to be described later with reference to FIG. 10, by a cross-sectional view cut along the X-Y' plane of the crystal piece 10. Further, FIG. 2(B) shows an image of the AT-cut crystal piece 10 with a thickness of tb (< ta) processed by a manufacturing method using a laser and wet etching to be described later with reference to FIG. 10, by a cross-sectional view cut along the X-Y' plane of the crystal piece 10.

[0020] When the thickness of the crystal piece 10 is ta or tb (< ta), as the wet etching progresses, the etching in the thickness direction (Y' direction) of the crystal piece 10 progresses. Also, during this wet etching, the first crystal plane 10e1 and the second crystal plane 10e2 are formed, and it has been found in the experiments of the inventor of the present application that the first crystal plane 10e1 and the second crystal plane 10e2 grow toward the center side of the crystal piece 10 while maintaining approximately the angles θa and θb with respect to the vertical plane 10f. Here, the meaning of maintaining approximately the angles θa and θb is that, although there are some differences depending on the depth in the thickness direction of the crystal piece in the crystal property disappearance region by laser irradiation described with reference to FIG. 10, the width in the direction along the main surface of the crystal piece, the wet etching time, the conditions of the etching mask during wet etching, etc., since the wet etching progresses within a certain range based on a certain crystal plane in the crystal planes of the crystal, θa and θb are within the above range. The validity of the above range for the angles θa and θb can also be said from the following experimental results of the inventor of the present application. That is, as an example in FIG. 2(A), when a crystal piece 10 with an initial thickness of 60 μm is used and laser irradiation and etching are performed, in the experiments where a crystal piece 10 with an initial thickness of 40 μm and a crystal piece 10 with an initial thickness of 26 μm are used as examples in FIG. 2(B) and laser irradiation and wet etching are performed, it has been found that in all cases of each crystal piece, θa and θb are within the range of 114° to 130°. However, when the thickness of the crystal piece 10 is thin (that is, when the thickness is tb), since the first crystal plane 10e1 and the second crystal plane 10e2 are combined earlier than when the thickness is ta, the vertical plane 10f disappears earlier and the end face becomes beak-shaped and only the inclined plane remains.

[0021] Considering these, for the end face on the +X side, a structure including the vertical plane 10f and the first crystal plane 10e1 and the second crystal plane 10e2 that intersect the vertical plane 10f at the angles θa and θb can be said to be an end face structure that allows the expansion of the vibration region. Furthermore, the inventor's experiments have revealed that the relationship between the first crystal plane 10e1 and the second crystal plane 10e2 with respect to the principal plane of the quartz crystal is as follows: The angle θ1 between the first crystal plane 10e1 and the principal plane 10ca, and the angle θ2 between the second crystal plane 10e2 and the principal plane 10cb, were in the range of 143 to 159°. In the example in Figure 1(B), it was 144°. Furthermore, if the wet etching time is extended, a third crystal plane 10e3 may be formed between the first crystal plane 10e1 and one main plane 10ca, and a fourth crystal plane 10e4 may be formed between the second crystal plane 10e2 and the other main plane 10cb, as shown in the SEM image in Figure 2(C). In this case as well, the tip of the +X side end of the crystal piece 10 is a vertical plane 10f, and the structure ensures that the vibration region as defined in this invention is maintained.

[0022] Furthermore, as shown in Figure 1(B), when the thickness of the portion where the main surfaces 10ca and 10cb of the quartz piece 10 face each other (thickness in the Y' direction in Figure 1(B)) is defined as t, and the dimension of the vertical surface 10f in the Y' direction is defined as t1, a larger t1 / t is preferable because it increases the proportion in which the side surface is perpendicular to the main surface, making it easier to secure the vibration region. While t1 / t is not limited to this, 30% or more is good, preferably 50% or more, and even more preferably 70% or more. In the case of the left diagram in Figure 1(B), t1 / t is approximately 74%, and in the case of Figure 2(C), t1 / t is approximately 56%.

[0023] 1-2-2. Second side surface 10ab of the first axis (side surface on the -X side) On the other hand, the second side surface 10ab of the first axis is, in this case, the -X side of the quartz crystal, which is one of the two sides that intersect the X axis of the quartz crystal. As shown on the right side of Figure 1(B), this second side surface 10ab of the first axis is composed of a first crystal plane 10e1 that is in contact with one main surface 10ca of the quartz crystal piece 10, a second crystal plane 10e2 that is in contact with the other main surface 10cb of the quartz crystal piece 10, and a plane 10f (also called a vertical plane 10f) that is between these first and second crystal planes 10e1 and 10e2, is in contact with these crystal planes, and has a contour 10fa parallel to the normal 11cc.

[0024] Furthermore, when the cross-section of the quartz piece 10 is cut along the XY' plane determined by the X and Y' axes, at the negative end of the X axis, the angle between the vertical plane 10f and the first crystal plane 10e1 connected thereto is defined as θc, and the angle between the vertical plane 10f and the second crystal plane 10e2 connected thereto is defined as θd, then θc is in the range of 90 < θc ≤ 158°, more specifically 149 ≤ θc ≤ 158°, and θd is in the range of 90 < θd ≤ 158°, more specifically 149 ≤ θd ≤ 158°. However, there are cases where θc = θd and cases where θc ≠ θd. Furthermore, when the thickness of the portion where the main surfaces 10ca and 10cb of the quartz piece 10 face each other (thickness in the Y' direction in Figure 1(B)) is defined as t, and the dimension of the vertical surface 10f in the Y' direction is defined as t1, t1 / t is not limited to this, but is preferably 30% or more, more preferably 50% or more, and more preferably 70% or more, and in this embodiment, t1 / t at the end face on the -X side is approximately 90%. The reason why it is preferable to set the angles θc and θd within the ranges of 149 ≤ θc ≤ 158° and 149 ≤ θd ≤ 158° is the same reason as the assertion of the ranges for angles θa and θb on the +X side end face mentioned above. In other words, these are angles determined by the inventor's experiments related to this application. The reason why the angles θa and θb on the +X side end face are different from the angles θc and θd on the -X side end face, and why t1 / t on the +X side end face is different from t1 / t on the -X side end face, is that the etching rate for wet etching of quartz is +X > -X.

[0025] 1-3. Both end surfaces of the quartz crystal along the Z' direction Next, with reference to Figure 1(C), the first side surface 10ba and the second side surface 10bb of the second axis will be described. In this case, the first side surface 10ba of the second axis is one of the two sides that intersect the Z' axis of the crystal, and the second side surface 10bb of the second axis is the other of the two sides that intersect the Z' axis of the crystal. In this embodiment, the first side surface 10ba and the second side surface 10bb of the second axis are each composed of a crystal plane 10e derived from quartz and a plane 10f (also called a vertical plane 10f) having a contour 10fa parallel to the normal 10cc of the main plane. Then, when we define θe as the angle between the crystal plane 10e and the perpendicular plane 10f on the first side surface 10ba of the second axis, and θf as the angle between the crystal plane 10e and the perpendicular plane 10f on the second side surface 10bb of the second axis, then θe is an angle in the range of 90 < θe ≤ 162°, more specifically 141 ≤ θe ≤ 162°, and θf is an angle in the range of 90 < θf ≤ 162°, more specifically 141 ≤ θf ≤ 162°. However, there are cases where θe = θf and θe ≠ θf. Typically, θe = θf. Furthermore, the reason why it is preferable to set the angles θe and θf within the ranges of 141≦θe≦162° and 141≦θf≦162° is the same reason as the assertion of the range of angles θa and θb on the +X side end face mentioned above: the inventor's experiments related to this application revealed that the angles θe and θf fall within the range of 141~162°.

[0026] Furthermore, when the thickness of the portion where the main surfaces 10ca and 10cb of the quartz piece 10 face each other at both ends along the Z' axis (thickness in the Y' direction in Figure 1(C)) is defined as t, and the dimension of the vertical surface 10f in the Y' direction is defined as t1, a larger t1 / t is preferable because it increases the proportion in which the side surface is perpendicular to the main surface, making it easier to secure the vibration region. While t1 / t is not limited to this, for example, 30% or more is good, preferably 50% or more, and even more preferably 70% or more. In this embodiment, t1 / t is approximately 74%. Furthermore, at both end faces of the quartz piece 10 along the Z' axis, the crystal plane 10e and the principal plane 10ca (10cb) intersect at an angle θ3. According to the inventor's experiments in this application, the angle θ3 is found to be in the range of 115 to 145 degrees. In addition, the crystal planes 10e of the first side surface 10ba and the second side surface 10bb, which are both sides of the quartz piece 10 along the Z' axis, are roughly point-symmetric with respect to the center point R of the quartz piece 10 (see Figure 1(C)). Furthermore, the following significant fact was discovered: In the case of the quartz piece 10 according to this invention, the crystal planes 10e on the first side surface 10ba and the second side surface 10bb along the Z' direction are located on the side of the two main surfaces of the quartz piece 10 that is opposite to the main surface on which the m-plane of the quartz can be generated. Each of these crystal planes 10e is considered to be a plane influenced by the r-plane (small R-plane), which is one of the crystal planes of the quartz. That is, in the case of the comparative example quartz piece 100, which will be explained later with reference to Figure 5, the crystal plane 100e is the m-plane of the quartz, as shown in Figure 5(B), and is located in the upper left and lower right parts of the quartz piece 100, whereas in the case of the quartz piece 10 according to this invention, as shown in Figure 1(C), unlike the comparative example, it is located in the upper right and lower left parts of the quartz piece 10. In other words, in the case of the quartz piece 10 according to this invention, both end faces in the Z' direction do not have the m-plane of the quartz.

[0027] In the above embodiment, an example was described in which the end faces along the Z' axis are composed of a surface 10f having a contour parallel to the normal of the main surface of the quartz piece 10 and a crystal surface 10e. However, as shown in Figure 3 (SEM photograph), the end faces along the Z' axis may also be composed of crystal surfaces 10x derived from quartz that are not parallel to the normal 10cc of the main surface of the quartz piece 10. In the example in Figure 3, the crystal surface 10x is composed of multiple crystal surfaces, in this case three crystal surfaces 10x1, 10x2, and 10x3. Even if both end faces along the Z' axis are composed of crystal planes 10x derived from quartz that are not parallel to the normal 10cc of the main surface of the quartz piece 10, at least the +X plane and -X plane of the quartz piece 10 are composed of a vertical plane 10f, a first crystal plane 10e1, and a second crystal plane 10e2, and include the vertical plane 10f, thus preventing a reduction in the vibration region in the X-axis direction. Furthermore, since the etching rate for wet etching between the crystal axes of quartz is Z plane > +X plane > -X, etching proceeds easily on the end faces along the Z' axis, and the vertical plane is more likely to disappear. However, even if the vertical plane disappears on both end faces along the Z' axis, as long as vertical planes 10f exist on the +X plane and -X plane of the quartz piece 10, the amount of loss of the vertical plane on the end faces along Z' is small, and therefore the amount of inclined plane on the Z' end faces is less than in the conventional method, thus reducing the vibration region of the quartz piece in the Z' direction compared to the conventional method.

[0028] According to the crystal piece 10 of this embodiment, each side surface 10aa, 10ab, 10ba, 10bb of the crystal piece has a structure that includes a surface 10f perpendicular to the main surfaces 10ca, 10cb. Therefore, compared to the case where this is not the case, that is, compared to the case where the side surfaces are made of inclined surfaces as in the conventional case, the usable region as the vibration region of the crystal piece 10 can be expanded.

[0029] 1-4. Condition of each side of the quartz crystal In this invention, it has been stated that a surface having a contour parallel to the normal of the main surface of a quartz crystal may be a crystalline surface, an amorphous surface, or a mixture of crystalline and amorphous surfaces. In this regard, SEM images of each side surface of the quartz crystal 10 of the embodiment show examples of the structure of each side surface. Figure 4 shows such an example. In the case of the quartz crystal 10 of the embodiment, it can be presumed that each of the surfaces 10f on each side surface 10ab, 10ab, 10ba, and 10bb, which have a contour parallel to the normal of the main surface, are crystalline surfaces of the quartz crystal.

[0030] 1-5. Shape of the corners of the quartz crystal Furthermore, focusing on the four corners of the crystal piece 10 in the embodiment, it has the following structure. That is, as shown in Figure 1(A), the four corners 10g, 10h, 10i, and 10j are right-angled corners when viewed from above. Right-angled means that the angle formed by the intersecting pieces is 90±2 degrees, preferably 90±1 degree. When the four corners 10g, 10h, 10i, and 10j are right-angled corners when viewed from above, it is preferable because it has the effect of expanding the vibration range of the crystal piece 10 compared to the case where it is not.

[0031] 1-6. Other Application Examples In the embodiments described above, an example was explained in which the present invention is applied to an AT-cut quartz crystal that is flat in shape and is rectangular overall. However, the present invention can also be applied to so-called tabletop-type AT-cut quartz crystals in which the vibrating part is thicker than the rest of the crystal. Furthermore, the present invention can also be applied to a quartz crystal that has undergone two rotations, such as an SC cut, which is obtained by rotating a plane perpendicular to the Y-axis of the quartz crystal by φ degrees around the Z-axis of the quartz crystal as the center of rotation, and then rotating it again by θ degrees around the X-axis of the quartz crystal as the center of rotation. In this case, the first axis is the X' axis derived from the two rotations, the second axis is the Z' axis derived from the two rotations, and the third axis is the Y' axis derived from the two rotations. Furthermore, the first invention can be applied to quartz crystals other than those with thickness-slip mode vibrations. For example, the first invention can also be applied to quartz crystals having contour-type vibration modes such as GT cuts.

[0032] 2. Comparative example quartz crystal To further understand the quartz crystal of the first invention, a comparative example quartz crystal 100 will be described with reference to Figure 5. Specifically, regarding the comparative example quartz crystal 100 manufactured using conventional photolithography and wet etching techniques, SEM images of each of the four sides of the crystal (two sides intersecting the X-axis and two sides intersecting the Z'-axis) are shown as a result of observation. Figure 5(A) is a comparative example corresponding to Figure 1(B), and Figure 5(B) is a comparative example corresponding to Figure 1(C). In the case of the comparative example quartz piece 100, the two sides intersecting the X-axis of the quartz (Figure 5(A)) are both composed of two inclined crystal planes 100a, 100b or 100c, 100d. Note that in Figure 5(A), the object indicated by 101 is an air bubble that formed in the embedding resin when preparing the cross-sectional observation sample, and is unrelated to the present invention. Furthermore, the two sides of the quartz crystal that intersect the Z' axis (Figure 5(B)) are both composed of a crystal plane 100e that intersects the main plane 100x of the quartz crystal piece 100 at an angle θx, and a crystal plane 100f that intersects the main plane 100x of the quartz crystal piece 100 at an angle θy. The angle between crystal plane 100e and crystal plane 100f is θz. And θx ≈ 143°, θy ≈ 92°, and θz ≈ 127°. Also, crystal plane 100e is the m-plane, which is one of the crystal planes of quartz. Therefore, it can be seen that the quartz piece 100 of the present invention and the quartz piece 100 of the comparative example differ in terms of the end face shape.

[0033] 3. Crystal device of the embodiment Next, the crystal device 20 of the embodiment will be described with reference to Figures 6(A) and (B). Figures 6(A) and (B) are explanatory diagrams of the crystal oscillator 20 as the crystal device 20 of the embodiment. In particular, Figure (A) is a top view thereof, and Figure (B) is a cross-sectional view of the crystal device 20 cut along the PP line in Figure (A). However, in Figure 6(A), the cover member 27 provided on the crystal device 20 is omitted. Also, Figure 6(A) is a diagram using an electron microscope (SEM) image of the crystal device 20 of the embodiment. The crystal oscillator 20 as a crystal device in this embodiment comprises a crystal piece 10 according to the first invention, a crystal resonator 21 having excitation electrodes 11 and extraction electrodes 11a provided on the main surfaces of the front and back of the crystal piece 10, and a container 23 enclosing the crystal resonator 21. In this example, the container 23 comprises a rectangular recess 23a in plan view for housing the crystal oscillator 21, a rim 23b surrounding the recess 23a, an adhesive pad 23c to which the crystal oscillator 21 is fixedly bonded, and an external connection terminal 23d provided on the outer bottom surface of the container 23 for connecting the crystal device 20 to any electronic device. The adhesive pad 23c and the external connection terminal 23d are electrically connected by via wiring or castellation (not shown). This container 23 can be made of a known ceramic package. In this case, the quartz crystal oscillator 21 has a cantilevered support structure. The quartz crystal oscillator 21 is connected and fixed to the adhesive pad 23c of the container 23 by conductive adhesive 25 at the position of the lead electrode 11a. A lid member 27 is joined to the top surface of the bank portion 23b of the container 23 in a structure corresponding to the sealing method, and the quartz crystal oscillator 21 is sealed inside the container 23.

[0034] In the above embodiment, a quartz crystal resonator was shown as an example of a quartz device. However, as shown in Figure 7, a quartz device 30 in which a quartz crystal 10 and other electronic components 31 such as a temperature sensor and an oscillation circuit are mounted inside a container 23, i.e., a quartz crystal resonator or quartz oscillator with a temperature sensor (including those with a temperature compensation function), is also included in the quartz device of the present invention. Furthermore, although a container 23 with a recess 23a has been shown, the container 23 may also be a container composed of a flat plate-shaped base and a cap-shaped lid member having a recess for housing the quartz crystal oscillator. Furthermore, although not shown in the diagram, the electronic device may have a so-called H-shaped structure, where the chamber housing the crystal oscillator and the chamber housing other electronic components such as the oscillator circuit are stacked back-to-back, and the cross-section cut along the stacking direction is also an H-shaped structure.

[0035] 4. Examination of electrical characteristics 4-1. Examples and Comparative Examples To further deepen our understanding of the present invention, we fabricated multiple prototypes of the quartz oscillators in the examples and comparative examples described below, measured their electrical characteristics, and examined the differences between them. As the crystal oscillator for the embodiment, a crystal piece 10 was used in which the +X end face, the -X end face, and both end faces along Z' had the structure described above using Figures 1(B) and (C), and a crystal oscillator 20 as shown in Figure 6 was fabricated. In other words, the crystal oscillator 20 was fabricated using a crystal piece 10 in which vertical surfaces remained on all end faces. In contrast, as the crystal oscillator for the comparative example, a crystal oscillator having the structure shown in Figure 6 was fabricated in the same way as the embodiment, except that the crystal piece 100 described using Figure 5 had excitation electrodes formed on the main surfaces of the front and back. The quartz crystals in the examples and comparative examples have the same external dimensions, but their end face structures differ as described above. In the examples, the end face has a vertical surface. In both the examples and comparative examples, the frequency was set to 76.8 MHz. Of course, the frequency is just an example and is not limited to it. Furthermore, as described above, the end face shapes of the quartz pieces in the examples and comparative examples are different, and therefore the dimensions of the inclined portions on the end faces are different, as explained below. Specifically, in the case of the quartz piece 10 according to the examples, the dimension X1 of the inclined portion on the +X side end face shown in Figure 1(B) is 3.3 μm, the dimension X2 of the inclined portion on the -X side end face shown in Figure 1(B) is 1.1 μm, the dimension Z1 of one of the inclined portions along the Z' axis at both ends shown in Figure 1(C) is 4.0 μm, and the dimension Z2 of the other inclined portion is 3.5 μm. Therefore, in the case of the quartz piece 10 according to the examples, the sum of the dimensions of the inclined portions at both ends along the X direction is 3.3 + 1.1 = 4.4 μm, and the sum of the dimensions of the inclined portions at both ends along the Z' direction is 4.0 + 3.5 = 7.5 μm.

[0036] In contrast, in the case of comparative example quartz piece 100, the dimensions corresponding to X1 and X2 were 6.6 μm and 4.9 μm, respectively, and the dimensions corresponding to Z1 and Z2 were 7.5 μm and 6.1 μm. Therefore, in the case of comparative example quartz piece 100, the sum of the dimensions of the inclined portions at both ends along the X direction is 6.6 + 4.9 = 11.5 μm, and the sum of the dimensions of the inclined portions at both ends along the Z' direction is 7.5 + 6.1 = 13.6 μm. Therefore, comparing the dimensions of the inclined portion of the quartz piece 10 in the example and the quartz piece in the comparative example, with the comparative example as the reference, the dimensions are 4.4 / 11.5 ≈ 0.38 in the X direction and 7.5 / 13.6 ≈ 0.55 in the Z' direction. Consequently, the dimension of the inclined portion of the quartz piece 10 in the example in the X direction is 38% smaller than the same dimension of the comparative example, and the dimension of the inclined portion of the quartz piece 10 in the example in the Z' direction is 55% smaller than the same dimension of the comparative example. Therefore, the example has a wider main surface area, that is, a wider area that can be used as a vibration region, compared to the comparative example. While the difference in the dimensions of the inclined section mentioned above may seem insignificant, it will become increasingly valuable as quartz devices become smaller and the planar shape of the quartz crystals becomes smaller and smaller. Furthermore, from the perspective of fabricating a large number of quartz crystals onto a quartz wafer, it is expected that this will allow for an increase in the number of quartz crystals that can be fabricated onto a single wafer.

[0037] Next, the crystal impedance (CI) of the quartz oscillators of the prototyped examples and comparative examples was measured at room temperature. Furthermore, the drive level characteristics of the quartz oscillators of the examples and comparative examples, i.e., the degree of frequency fluctuation of the quartz oscillators when the power driving each quartz oscillator was changed, were measured. Figure 8(A) is a histogram showing the CI distribution of the quartz oscillators of the examples and comparative examples at room temperature. Figure 8(B) shows the rate of frequency change (ppm) for the quartz oscillators of the examples and comparative examples with respect to the initial power when the drive level (μW) is changed. From the CI distribution in Figure 8(A), it can be seen that the CI of the crystal oscillator in the example is equivalent to or slightly better than that of the crystal oscillator in the comparative example. Furthermore, from the drive level characteristics in Figure 8(B), it can be seen that the drive level characteristics of the crystal oscillator in the example are superior to those of the crystal oscillator in the comparative example. Therefore, the quartz crystal of the present invention is useful for improving the characteristics of quartz devices and for preventing a reduction in the vibration range of the quartz crystal.

[0038] Example of dimensional analysis for 4-2.76.8MHz crystal fragments Crystal oscillators with an oscillation frequency of 76.8 MHz (including those with built-in thermistors) are useful as reference oscillators for various electronic devices such as mobile phones. Therefore, we investigated the preferred dimensional ranges for AT-cut crystal oscillators that are favorable for the electrical characteristics and mass production of 76.8 MHz crystal oscillators, specifically the X-dimension (along the X-axis) and Z-dimension (along the Z'-axis). The results are described below. The inventor of this application fabricated a crystal device 20, or crystal oscillator 20, shown in Figure 6, using a crystal piece 10 shown in Figure 1, wherein the dimension Lx along the X-axis of the crystal and the dimension Lz along the Z'-axis of the crystal (see Figure 6(A)) are set to multiple dimensions as described below. Lx (unit: mm): 5 levels: 0.7391, 0.7416, 0.7441, 0.7446, 0.7491. Lz (unit: mm): 9 levels: 0.5035, 0.506, 0.5085, 0.511, 0.5135, 0.516, 0.5185, 0.521, 0.5235.

[0039] The crystal impedance (CI) of each prototype quartz device fabricated with these dimensions was measured. The results of this measurement are summarized in Figures 9(A) and 9(B). Figure 9(A) shows the CI distribution of each prototype, with dimension Lx on the horizontal axis and CI (relative value) on the vertical axis. Figure 9(B) shows the CI distribution of each prototype, with dimension Lz on the horizontal axis and CI (relative value) on the vertical axis. Specifically, in Figure 9(A), the vertical plots in each figure for dimension Lx represent the CI distribution of each prototype with different dimensions Lz relative to Lx, and in Figure 9(B), the vertical plots in each figure for dimension Lz represent the CI distribution of each prototype with different dimensions Lx relative to Lz. The CI specification for these prototypes is preferably 4 or less in relative value, and more preferably 3.5 or less. From Figures 9(A) and (B), the range of the prototype was generally favorable. However, if we were to be specific, from Figure 9(A), within the range of the prototype, dimensions Lx larger than 0.739 mm would be preferable. Also, from Figure 9(B), within the range of the prototype, the minimum CI range for dimension Lz is around Lz = 0.511 to 0.516 mm.

[0040] The following table summarizes the measurement results of the above-mentioned CI from different perspectives. This table calculates the average value Avg and the standard deviation σ of the CI of the entire above-mentioned prototype, and also calculates the average value of the CI of the prototype for each combination of the dimension Lx and the dimension Lz, and shows which level the average value of the CI of the prototype for each combination of the dimension Lx and the dimension Lz corresponds to when viewed in light of the average value Avg and the standard deviation σ of the CI of the entire above-mentioned prototype. The cells marked with Avg in each cell of the table mean the level indicating the CI at the same level as the average value Avg of the CI of the entire prototype, the cells marked with +0.5σ in each cell of the table mean the level indicating the CI at the +0.5σ level with respect to the average value Avg of the CI of the entire prototype, the cells marked with -0.5σ in each cell of the table mean the level indicating the CI at the -0.5σ level with respect to the average value Avg of the CI of the entire prototype, and hereinafter, ···+1.5σ···-1.5σ, etc. have the same meaning.

[0041] Considering FIG. 9(A), FIG. 9(B) and the following table, an example of a preferable size of an AT-cut quartz crystal piece with an oscillation frequency of 76.8 MHz, when shown by the dimension Lx along the X-axis of the quartz and the dimension Lz along the Z'-axis of the quartz, 0.7391 mm < Lx ≦ 0.7491 mm, and 0.5035 mm ≦ Lz ≦ 0.5235 mm it can be said that. When shown by the ratio (so-called side ratio) to the thickness 0.0182 mm of the AT-cut quartz crystal piece with an oscillation frequency of 76.8 MHz, 40.61 < Lx / quartz crystal piece thickness ≦ 41.15, and 27.66 ≦ Lz / quartz crystal piece thickness ≦ 28.76 it can be said that. Also, more preferably, Lx and Lz are 0.7416 mm < Lx ≦ 0.7491 mm, and 0.5035 mm ≦ Lz ≦ 0.5235 mm it can be said that it is good.

[0042] In the above discussion, we examined preferred dimensions for an AT-cut quartz crystal with an oscillation frequency of 76.8 MHz. However, we believe that the above dimensional range can also be applied to AT-cut quartz crystals with other oscillation frequencies around 76.8 MHz, such as 76.8 ± 1 MHz. In that case, the dimensions Lx and Lz may deviate slightly from the above range, but in that case, the above range can be corrected by adjusting Lx and Lz using the side ratio, which is the ratio of the thickness of the quartz crystal to the dimensions Lx and Lz. TIFF2026057473000002.tif47156

[0043] 5. Examples of manufacturing methods for quartz crystal pieces 10 and intermediate wafers for quartz device formation. Next, with reference to Figures 10(A) to (D), an example of a manufacturing method for the quartz piece 10 of the first invention (an embodiment of the fourth invention) and an embodiment of an intermediate wafer for a quartz device, which is the third invention, will be described. Figures 10A) to (D) are the main parts of the manufacturing process diagram for that purpose. Figures 10(B) and (C) are cross-sectional views along the PP line in Figure 10(A). First, an AT-cut quartz wafer 50 is prepared (Figure 10(A)). Next, a laser beam, preferably an ultrashort pulse laser beam, is irradiated along the planned outer edge portion 50a of the quartz pieces 10 on the quartz wafer 50 to form a crystalline loss region 50b along the thickness direction of the quartz wafer on the planned outer edge portion 50a (Figure 10(B)). Note that when irradiating with the laser, the laser is not irradiated onto the portion 50c (see Figure 10(A)) that connects each quartz piece 10 to the quartz wafer 50. Furthermore, since the crystalline loss region 50b is formed by laser irradiation, the width W (see Figure 10(B)) of the crystalline loss region 50b can be narrow, resulting in the effect of being able to increase the number of quartz pieces 10 in the quartz wafer 50.

[0044] The quartz wafer, in which the crystallinity-disappearing region 50b has been formed, is immersed in a wet etching etchant, such as a hydrofluoric acid-based etchant (not shown), to remove the region including the planned outer edge of the quartz wafer and to penetrate the quartz wafer, thereby forming the outer shape of the quartz pieces 10 (Figure 10(C)). In this etching process, etching of the crystallinity-lost region 50b of the quartz wafer 50 proceeds faster than etching of the crystalline region. Therefore, etching time can be shortened compared to conventional manufacturing methods using photolithography and wet etching techniques. Furthermore, during the wet etching process, the area near the surface of the quartz wafer 50 is etched in a direction intersecting the thickness direction of the quartz wafer 50, creating a crystal plane 10e. The dimensions of the crystal plane 10e vary depending on the length of the etching time. On the other hand, the plane parallel to the normal of the main surface of the quartz wafer (the plane 10f shown in Figure 1, etc., the vertical plane 10f) will have a region of crystallinity loss remaining if the wet etching time is short, and will have a vertical plane 10f with a crystal plane of quartz while maintaining its vertical plane if the wet etching time is appropriate. If the wet etching time is long, the vertical plane 10f will disappear and an inclined crystal plane will be created. However, since the objective of the present invention is to form a vertical plane 10f on the side surface of the quartz piece, wet etching is performed for a time that allows the vertical plane to remain. This results in a quartz wafer having many quartz pieces, each having a plane 10f with a contour 10fa parallel to the normal of the main surface 10c of the quartz piece 10.

[0045] As can be seen from the above, by adjusting the immersion time of the quartz wafer, in which the crystallinity-disappearing region 50b has been formed, in the etchant for wet etching, the ratio between the dimension in the thickness direction of the quartz wafer on the vertical plane 10f (the dimension shown as t1 in Figure 1, etc.) and the crystal planes of quartz origin connected to the vertical plane can be controlled. Next, excitation electrodes 11 are formed on the front and back surfaces of each quartz crystal 10 using known film deposition and photolithography patterning techniques. These steps allow for the formation of an intermediate wafer 50x for quartz device formation. That is, a quartz wafer 50x can be formed that has a large number of quartz crystals 10, each equipped with excitation electrodes 11 on its main front and back surfaces, arranged in a matrix (Figure 10(D)). Subsequently, this quartz wafer 50x is subjected to a division process, for example, using known dicing techniques, to obtain the quartz crystals 10 shown in Figure 1. Alternatively, to separate the quartz crystals from the quartz wafer, a break-off groove may be provided at the connection point between the quartz crystal and the frame of the quartz wafer, and the quartz crystal may be broken off from the quartz wafer starting from this groove. [Explanation of Symbols]

[0046] 10: Crystal piece of the embodiment, 10a: First axis (X axis of the crystal) 10b: Second axis (Z' axis of the quartz crystal) 10ca: One principal surface of the quartz crystal 10cb: The other principal surface of the quartz crystal, 10cc: The normal to the principal surface 10d: Third axis (Y' axis of the crystal) 10aa: First side of the first axis 10ab: Second side of the first axis 10ba: First side of the second axis 10bb: Second side of the second axis 10e: Crystal face of quartz 10e1: First crystal face 10e2: Second crystal plane; 10f: Plane parallel to the normal (plane perpendicular to the principal plane) 10fa: Contour of surface 10f 10g, 10h, 10i, 10j: The four corners of the quartz crystal 11: Excitation electrode, 11a: Extraction electrode, 20: Crystal device (crystal oscillator) of the embodiment 21: Crystal vibrating piece, 23: Container, 23a: recess, 23b: embankment, 23c: Adhesive pad, 23d: External connection terminal 25: Conductive adhesive, 27: Lid material 30: Piezoelectric device of another embodiment 31: Other electronic components (temperature sensor, oscillator circuit, etc.) 50: AT-cut quartz wafer L: Laser light 50a: Planned outer edge 50b: Crystalline loss region 50x: Intermediate wafer for crystal device formation

Claims

1. In a quartz piece that is rectangular in shape when viewed from above, the first axis-second axis plane, defined by the first axis originating from the X-axis of the quartz and the second axis originating from the Z-axis of the quartz, is the main plane, and the third axis originating from the Y-axis of the quartz is the thickness direction. When one of the surfaces of the quartz crystal that intersects the first axis is defined as the first surface of the first axis and the other as the second surface of the first axis, and when one of the surfaces of the quartz crystal that intersects the second axis is defined as the first surface of the second axis and the other as the second surface of the second axis, The first side surface and the second side surface of the first axis are each composed of a crystal plane derived from quartz and a plane having a contour parallel to the normal of the main plane. A quartz piece characterized in that the first side surface of the second axis and the second side surface of the second axis are each composed of a crystal plane derived from quartz and a plane having a contour parallel to the normal of the main surface, or composed of a crystal plane derived from quartz that is not parallel to the normal of the main surface.

2. The crystal piece according to claim 1, characterized in that when the thickness of the crystal piece is t and the length along the third axis of the surface having a contour parallel to the normal is t1, t1 / t ≥ 0.

5.

3. The quartz piece according to claim 1, characterized in that the crystal plane includes a crystal plane whose one end is continuous with one of the main surfaces of the front and back of the quartz piece, and a crystal plane whose one end is continuous with the other main surface of the front and back of the quartz piece.

4. The quartz piece according to claim 1, characterized in that the crystal plane includes a crystal plane whose one end is continuous with one of the main surfaces of the front and back of the quartz piece, a crystal plane whose one end is continuous with the other main surface of the front and back of the quartz piece, and yet another crystal plane.

5. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The quartz piece according to claim 1, characterized in that the third axis is the Y' axis which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut.

6. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The first side surface of the second axis and the second side surface of the second axis are each composed of a crystal plane derived from quartz and a plane having a contour parallel to the normal of the main plane. The quartz piece according to claim 1, characterized in that the crystal planes originating from quartz that occur on the first and second sides of the second axis are crystal planes that occur on the side of the main surface opposite to the side of the main surface where an m-plane, which is one of the crystal planes of quartz, can occur.

7. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The crystal piece according to claim 1, characterized in that the surfaces on each of the two sides along the X-axis, which have a contour parallel to the normal, have a rough surface.

8. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The cross-section of the quartz piece cut along the X-Y' plane determined by the X-axis and Y'-axis includes, at the positive end face of the X-axis, a plane having a contour parallel to the normal and a first crystal plane and a second crystal plane connected thereto, When the angle between the plane having a contour parallel to the normal and the first crystal plane is defined as θa, and the angle between the plane having a contour parallel to the normal and the second crystal plane is defined as θb, The quartz piece according to claim 1, characterized in that 114° ≤ θa ≤ 130° and 114° ≤ θb ≤ 130°.

9. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The cross-section of the quartz piece cut along the X-Y' plane determined by the X-axis and the Y'-axis includes, at the negative end of the X-axis, a surface having a contour parallel to the normal and a first crystal plane and a second crystal plane connected thereto. When the angle between the plane having a contour parallel to the normal and the first crystal plane is defined as θc, and the angle between the plane having a contour parallel to the normal and the second crystal plane is defined as θd, The quartz piece according to claim 1, characterized in that 149° ≤ θc ≤ 158° and 149° ≤ θd ≤ 158°.

10. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The cross-section of the quartz crystal, cut along the Y'-Z' plane determined by the X-axis and the Y'-axis, includes, at both ends in the Z'-axis direction, a plane having a contour parallel to the normal and a crystal plane connected thereto, The angle between the plane having a contour parallel to the normal and the crystal plane at one end in the Z' axis direction is defined as θe. The angle between the plane having a contour parallel to the normal and the crystal plane at the other end in the Z' axis direction is defined as θf. When that happened, The quartz piece according to claim 1, characterized in that 141° ≤ θe ≤ 162° and 141° ≤ θf ≤ 162°.

11. The aforementioned quartz piece is an AT-cut quartz piece. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. The cross-section of the quartz piece cut along the X-Y' plane determined by the X-axis and the Y'-axis includes, at the positive end of the X-axis, a plane having a contour parallel to the normal and a first crystal plane and a second crystal plane connected thereto, When the angle between the plane having a contour parallel to the normal and the first crystal plane is defined as θa, and the angle between the plane having a contour parallel to the normal and the second crystal plane is defined as θb, 114°≦θa≦130° and 114°≦θb≦130°, The cross-section of the quartz piece cut along the X-Y' plane determined by the X-axis and Y'-axis includes, at the negative end of the X-axis, a plane having a contour parallel to the normal and a first crystal plane and a second crystal plane connected thereto, When the angle between the plane having a contour parallel to the normal and the first crystal plane is defined as θc, and the angle between the plane having a contour parallel to the normal and the second crystal plane is defined as θd, 149°≦θc≦158° and 149°≦θd≦158°, The cross-section of the quartz piece cut along the Y'-Z' plane determined by the X-axis and the Y'-axis includes, at both ends in the Z'-axis direction, a plane having a contour parallel to the normal and a crystal plane connected thereto. The angle between the plane having a contour parallel to the normal and the crystal plane at one end in the Z' axis direction is defined as θe. When the angle between the plane having a contour parallel to the normal and the crystal plane at the other end in the Z' axis direction is defined as θf, The crystal piece according to claim 1, characterized in that 141° ≤ θe ≤ 162° and 141° ≤ θf ≤ 162°.

12. The aforementioned quartz piece is a quartz piece that has undergone two rotations, obtained by rotating a plane perpendicular to the Y-axis of the quartz by φ degrees around the Z-axis of the quartz as the center of rotation, and then rotating it again by θ degrees around the X-axis of the quartz as the center of rotation. The first axis is the X' axis derived from the two rotations, The second axis is the Z' axis derived from the two rotations, The crystal piece according to claim 1, characterized in that the third axis is the Y' axis derived from the two rotations.

13. In a quartz crystal piece that is rectangular in shape when viewed from above, the first axis-second axis plane, defined by the first axis originating from the X-axis of the quartz and the second axis originating from the Y-axis of the quartz, is the main plane, and the third axis originating from the Z-axis of the quartz is the thickness direction. When one of the surfaces of the quartz crystal that intersects the first axis is defined as the first surface of the first axis and the other as the second surface of the first axis, and when one of the surfaces of the quartz crystal that intersects the second axis is defined as the first surface of the second axis and the other as the second surface of the second axis, The first side surface of the first axis, the second side surface of the first axis, the first side surface of the second axis, and the second side surface of the second axis, A quartz crystal piece characterized by being composed of crystal faces derived from quartz and vertical faces having contours parallel to the normal of the main faces.

14. The aforementioned quartz crystal is an AT-cut quartz crystal with an oscillation frequency of around 76.8 MHz. The first axis is the X-axis of the crystal, The aforementioned second axis is the Z' axis, which is shifted from the Z axis of the crystal due to the cutting angle of the AT cut. The aforementioned third axis is the Y' axis, which is shifted from the Y axis of the quartz due to the cutting angle of the AT cut. When the dimension of the quartz crystal along the X-axis is defined as Lx and the dimension along the Z'-axis is defined as Lz, Lx, Lz 0.7391mm<Lx≦0.7491mm, 0.5035mm≦Lz≦0.5235mm The crystal piece according to claim 1, characterized in that it is the same as the one described in claim 1.

15. The quartz piece according to any one of claims 1 to 14, characterized in that the four corners of the square-shaped quartz piece are right-angled corners when viewed from above.

16. A quartz device comprising a quartz crystal disc described in any one of claims 1 to 14, an excitation electrode provided on the main surfaces of the front and back of the quartz crystal disc, and a container enclosing the quartz crystal disc.

17. A crystal device comprising a crystal piece according to any one of claims 1 to 14, wherein the four corners of the crystal piece are right-angled corners when viewed from above, and a crystal vibrator provided on the main surfaces of the front and back of the crystal piece for excitation, and a container enclosing the crystal vibrator.

18. A crystal vibrator comprising a crystal piece according to any one of claims 1 to 14 and excitation electrodes provided on the main surfaces of the front and back of the crystal piece, and a container enclosing the crystal vibrator, The crystal device is characterized by being a crystal resonator, a crystal resonator with a temperature sensor, or a crystal oscillator.

19. A crystal quartz crystal according to any one of claims 1 to 14, comprising a crystal quartz crystal whose four corners are right-angled when viewed from above, and a crystal quartz vibrating element provided on the main surfaces of the front and back of the crystal quartz crystal, and a container enclosing the crystal quartz vibrating element, The crystal device is characterized by being a crystal resonator, a crystal resonator with a temperature sensor, or a crystal oscillator.

20. An intermediate wafer for a quartz device, characterized by comprising a quartz wafer having a large number of quartz vibrating pieces arranged in a matrix, each vibrating piece having a quartz piece and excitation electrodes provided on the front and back surfaces of the quartz piece, as described in any one of claims 1 to 14.

21. An intermediate wafer for a quartz device, characterized in that it comprises a quartz wafer having a large number of quartz vibrating pieces arranged in a matrix, the quartz pieces having four right-angled corners when viewed from above, and excitation electrodes provided on the front and back surfaces of the quartz pieces.

22. In manufacturing the quartz crystal piece according to any one of claims 1 to 14, The process of preparing the quartz wafer, A step of irradiating the quartz wafer with laser light along the planned outer edge portion of the quartz crystal to form a region of crystal loss in the thickness direction of the quartz wafer at the planned outer edge portion, The process involves immersing the quartz wafer, in which the crystallinity-disappearing region has been formed, in an etchant for wet etching to remove a predetermined amount of the region including the outer edge region of the quartz wafer, thereby forming the outer shape of the quartz piece. A method for manufacturing quartz crystals, characterized by including the following:

23. The method for manufacturing a quartz piece according to claim 22, characterized by adjusting the immersion time of the quartz wafer in the etchant to control the dimension of the surface having a contour parallel to the normal of the main surface along the normal.

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